1. Field of the Invention
The present invention relates to a structure for a symmetrically disposed linear motor operated tool machine, in particular, to the structure of a tool machine which is driven by symmetrically disposed high output linear motors that allow the machine to evade structural deformation.
2. Description of the Prior Art
The basic structural strength and working precision for conventional tool machines can be achieved by precise control of the servo motors and ball screws which are used as a driving source.
The need for high working speed and output of tool machines has become greater and greater in order to keep pace with the development of the high speed machine technology which weeds out the conventional tool machines operated by servo motors and ball screw units. Now the linear motor driving system appears on the stage to solve this problem timely. The strong driving force generated by high intensity electric and magnetic fields of the windings and the permanent magnets operate the tool machines precisely with high speed but with very little contact frictional resistance loss.
In the meanwhile, those C type or inverse U type frame structures that have been used satisfactorily for a long time along with the conventional tool machines operated by servo motors or ball screw units now encounter a doubtful problem as to if it possible for these structures to serve for the modern high speed and high output tool machines which are driven by the linear motors that might exert strong deformational even destructive force produced by armature reaction between the winding current and the magnetic field to the machine structures.
US 2002/0047319 and EP1186374 disclose tool machines using the linear motors for driving. But, similar to other conventional techniques, the tool machines according to these two cited publications are unable to eliminate the aforementioned shortcomings due to asymmetrical disposal of the linear motors. Besides, in addition to low efficiency and speed caused by insufficient driving force, the backlash and sags among transmission components such as screws and gears, results in a failure to maintain the necessary working precision of the tool machines.
It is what the reason the inventor of the present invention has endeavored for years by continuous research and experimentation trying to find out the remedy to rectify the inherent shortcomings common to the conventional techniques described above, and finally has come to realization of the present invention.
It is an object of the present invention to provide a structure for symmetrically disposed linear motor operated tool machine which is capable of generating several times of driving force than a conventional one to improve the working efficiency of a tool machine.
It is another object of the present invention to provide a structure for symmetrically disposed linear motor operated tool machine which is capable of operating with many times of working accuracy than a conventional machine employing servo motors or ball screw units by using small inertia, backlashless and frictionless linear motors.
It is still another object of the present invention to provide a structure for symmetrically disposed linear motor operated tool machine whose slide rails are free from overload and the machine structure is never deformed by symmetrically disposing the linear motors so as to compensate the armature reactional force coming from individual motors.
It is one more object of the present invention to provide a structure for symmetrically disposed linear motor operated tool machine which is supported by two parallelly standing walls at two sides to intensify the structural strength.
To achieve these and other objects mentioned above, the structure of the present invention comprises two parallelly standing sustaining walls, a movable gantry, a sliding saddle, a tool spindle, and a weight compensation device. Wherein, at both sides of the movable gantry between the sustaining walls, between the sliding saddle and the movable gantry, and between the tool spindle and the sliding saddle, pairs of linear motors are symmetrically disposed such that the armature reaction arising between windings and magnets of linear motors is compensated each other by the opposite one therefore eliminating any extra exerting force to deform or destroy the structure or causing overload to the slide rails. The parrallelly standing sustaining walls also contribute to symmetry of the entire structure and serve to intensify the structural strength.